Cloning and expression of single chain antibody fragments in Escherichia coli and Pichia pastoris

The potential of recombinant antibody fragments is likely to be fulfilled only if they can be produced routinely at high concentrations. We have compared the ability of Escherichia coli and Pichia pastoris to produce functional recombinant single chain antibody (scAb) fragments. Two scAb fragments were expressed, an antihuman type V acid phosphatase (TRAP) and an anti-Pseudomonas aeruginosa lipoprotein I. We report here that, while expression from P. pastoris resulted in a significantly increased level of expression of the anti-TRAP scAb compared to E. coli, neither fragment was able to bind its target antigen as well as the bacterial product.     

Effects of ovariectomy on aggregation,secretion, and metalloproteinases in porcine platelets

Differences in the aggregation and release of growth factors including matrix metalloproteinases (MMPs) after loss of ovarian hormones could contribute to an exaggerated response to injury in arteries of ovariectomized animals. Therefore, experiments were designed to compare aggregation, dense granular ATP release, expression of MMPs (MMP-2, MMP-9, and MMP-14) and tissue inhibitors of metalloproteinase (TIMP-1 and TIMP-2) in circulating platelets from sexually mature (7 mo old) gonadally intact and ovariectomized (4 wk) female pigs. Numbers of circulating platelets did not change after ovariectomy, but the percentage of reticulated platelets increased significantly. Platelet aggregation and dense granular ATP secretion also increased significantly with ovariectomy. In platelet lysates, active MMP-2 increased, whereas MMP-14 significantly decreased, after ovariectomy; the expression of TIMP-1, TIMP-2, and P-selectin did not change. These results suggest that platelet turnover, aggregation, and ATP secretion increase with ovariectomy. Also, ovarian hormones selectively regulate the expression and activity of MMPs in porcine platelets. Increased platelet aggregation and activity of MMP-2 would alter platelet-platelet and platelet-vessel wall interactions, contributing to an exaggerated response to injury with loss of ovarian hormones.     

The ARF-like GTPases Arl1p and Arl3p act in a pathway that interacts with vesicle-tethering factors at the Golgi apparatus

The ARLs are a diverse family of GTPases that are related to ADP-ribosylation factors (ARFs), but whose function is poorly understood. There are at least ten ARLs in humans, two of which have homologs in the yeast Saccharomyces cerevisiae (ARL1/Arl1p and ARFRP1/Arl3p). The function of ARFRP1 is unknown, but mammalian ARL1 has recently been found to interact with a number of effectors including the GRIP domain that is present in a family of Golgi-localized long coiled-coil proteins. We find that in yeast, the intracellular targeting of Imh1p, the only yeast GRIP domain protein, is dependent on both Arl1p and Arl3p, but not on the ARF proteins. A recombinant form of the Imh1p GRIP domain binds to Arl1p in a GTP-dependent manner, but not to Arl3p. Yeast also contain a relative of SCOCO, a protein proposed to bind human ARL1, but this yeast protein, Slo1p, appears to bind Arl3p rather than Arl1p in vitro. However, Imh1p is not the sole effector of Arl1p since affinity chromatography of cytosol with immobilized Arl1p:GTP revealed an interaction with the GARP/VFT complex that is thought to act in the tethering of vesicles to the Golgi apparatus. Finally, we find that Arl3p is required in vivo for the targeting of Arl1p, explaining its requirement for the normal distribution of Imh1p.     

Dissolved oxygen in the porcine gastrointestinal tract

Dissolved oxygen concentrations in gut contents in situ were measured in anaesthetized piglets by the electrode and membrane-inlet mass spectrometric methods. Very high concentrations of oxygen were observed throughout the gut. In the duodenum and jejunum, values approaching air-saturation were recorded. Taken together with previous findings on the distribution of anaerobes in the gut, it seems that the dissolved oxygen concentration may be an important factor determining the activity and composition of the pig gut microbial flora.     

Adhesion molecule expression and infiltrating maternal leucocyte phenotypes during blastocyst implantation in the pig

During the implantation period (days 14 to 30 post coitum) in Large White pigs substantial numbers of endometrial sub-epithelial leucocytes were observed from about day 18 p.c. These were predominantly MHC Class II⁺, CD45⁺ and reactive for an accessory cell determinant carried by polymorphs and macrophages. Maternal lymphocytes of the CD2⁺, CD4^?, CD8^?, and a γδTcR⁺ subtype identified by the mAb 86D, were also present. Few CD4⁺, CD8⁺, or double-positive lymphocytes were seen. CD2^?CD4^?CD8^? γδTcR⁺ "Null" cells were seen in stroma adjacent to endometrial glands, as were CD2⁺ lymphocytes. There was no apparent upregulation of CD18, VLA-4 or CD25. E-selectin could not be detected on endothelium within uterine tissues or on trophectoderm, nor was a ligand for L-selectin detectable. The luminal aspect of the uterine epithelium was strongly reactive with anti-CD15 mAb, which was specifically blocked by lacto-N-fucopentaose III, indicating the presence of the Lewis^X determinant.     

An enzyme-p.m.r.-spectroscopic determination of the enantiomers of galactose

The action of d-galactose oxidase on d-galactose in the presence of oxygen afforded meso-galacto-hexodialdose quantitatively, which allowed p.m.r.-spectroscopic determination of the d enantiomer in a dl mixture. In the spectrum of the products obtained from the enzymic treatment of a mixture of d- and l-galactose, the magnitude of the aldehydrol signals derived solely from the oxidised d enantiomer, relative to those of the anomeric signals, provided the fractional content of the d enantiomer. This simple, accurate, and convenient procedure was applied to the hydrolysate of a seaweed galactan, which was also analyzed, for comparative purposes, by the fermentation technique employing d-galactose-adapted Saccharomyces cerevisiae.